1. Field of the Invention
The present invention relates to spliced joints and connections for wires, optical fiber cables and the like and, more particularly, to a method and apparatus for making heat sealed spliced joints and connections.
2. Description of the Prior Art
Using heat shrinking techniques for providing protection to joints, connections and splices between electrical cables, optical fiber cables, and the like has long been an accepted practice. During the joining and splicing of cables, it is often necessary to branch cables, whereby a large cable coming into a joint is branched into two cables going out of the joint. This is often called a "Y" transition. When such joints are formed utilizing adhesive lined heat shrinkable tubes or sleeves to environmentally isolate the joint, it is well established that by using tools, such as long needle nosed pliers, it is possible to form a seal between the two outgoing cables. It is necessary to squeeze down on the area between the outgoing cables because the heat shrinkable material tends to form in straight lines across the outgoing cables and refuses to come together in this area by itself.
In an article by Raychem Corporation in 1968 entitled "Thermofit Tubing Splice Ecapsultion Directions", the procedure for making a splice is described. Two wires are twistedly connected and the entire connection is then sealed using a heat shrinkable tubing. While the tubing is still hot, a needle nose pliers is used to close down the heat shrinkable material extending between the pair of wires. This technique does not create a smooth joint because of the interaction between the sharp edges on the pliers and the heat shrinkable material. Additionally, this technique inconveniently requires the user to hold the pliers and exert pressure thereon during the joint forming process.
Another form of splice seal is shown in U.S. Pat. No. 4,085,286 owned by Raychem Corporation. A heat recoverable material is first clamped, heated and expanded to form an enlarged version of the splice seal. The cables to be joined are then put in place and the previously formed heat recoverable material is clamped, heated and shrunk to form the desired environmentally encapsulated splice.
In U.S. Pat. No. 4,123,047, also owned by Raychem Corporation, a series of hand operated clips are used to hold a heat shrinkable material wrapped on an object to be shrink wrapped. Each clip has a pair of bond line gripping flanges attached to a pair of ventilated cooperating jaw plates to squeeze the material together along a bond line.
Another device for preparing "Y" transition joints is shown in Raychem Corporation's U.S. Pat. No. 4,648,924. It comprises, in one embodiment, an elongated clip having a pair of legs joined at one end whereby a channel is found therebetween. After an incoming cable and two outgoing cables are joined and heat shrinkable tubing is inserted thereover, the elongated clip is inserted into the area between the outgoing cables to grasp the heat shrinkable material therein and hold it together. Thereafter, heat is supplied to heat shrink the material and seal the joint. However, the size of the clip makes it difficult to insert and remove, especially when the area is hot.
The present invention is designed to overcome the above-noted limitations that are attendant upon the use of the foregoing prior art methods and devices. Toward this end, it contemplates the provision of a novel method and apparatus for heating sealing joints and connections which include a spring loaded tool so the user does not have to be skilled in forming branching joints with heat shrinkable material.
It is an object of the invention to provide a novel method and apparatus in which the clamp can be employed before, during or after the application of heat to the heat shrinkable material around the joint being sealed.
It is also an object to provide such a method and apparatus to eliminate the hazard and inconvenience presented by the prior art procedures and devices.
Still another object is to provide such a method and apparatus in which the clamp has smooth, convex clamping jaws without sharp edges to contact the heat shrinkable material.
A further object is to provide such an apparatus which may be readily and economically fabricated and will enjoy a long life in operation.